This application is based on Japanese Patent Application Nos. 11-225372 filed Aug. 9, 1999 and 2000-172059 filed Jun. 8, 2000, the contents of which are incorporated hereinto by reference.
1. Field of the Invention
The present invention relates in general to a vehicle stability control apparatus adapted to assure stable running of an automotive vehicle, and more particularly to techniques for improving running safety of the vehicle.
2. Discussion of Related Art
A so-called xe2x80x9cvehicle stability control (VSC)xe2x80x9d is known, wherein a vehicle running stability control device is operated under a hazardous running condition of an automotive vehicle, to apply a brake to at least one wheel of the vehicle, and/or reduce an output of an engine of the vehicle, as disclosed in U.S. Pat. No. 5,873,802 by was of example. Under some running conditions of the vehicle, a vehicle running stability control is not sufficient or effective to assure stable running or turning of the vehicle, namely, to safely clear an obstacle or prevent a collision of the vehicle with the obstacle, or to prevent a deviation of the running vehicle from the nominal running path or traffic lane of the vehicle. JP-A-10-264795 discloses an example of an improved vehicle stability control apparatus which is adapted to deal with such a problem that may happen under severe vehicle running conditions beyond the capacity of the conventional vehicle stability control. This apparatus is equipped with a CCD (charge-coupled device) camera for obtaining an image of a scene in front of the vehicle as seen by the vehicle operator in the vehicle running direction. Described more specifically, the improved vehicle stability control apparatus incorporates obstacle-clearance determining means for detecting an obstacle which lies in front of the vehicle in a running path of the vehicle, on the basis of image data obtained by the CCD camera, and for determining whether it is possible to control the vehicle so as to prevent a collision of the vehicle with the obstacle. When the obstacle-clearance determining means determines that the vehicle running stability control does not permit the vehicle to be adequately controlled so as to clear the detected obstacle, the vehicle stability control apparatus terminates its vehicle stability control upon detection of a vehicle operator""s manipulation to prevent a collision of the vehicle with the obstacle.
The vehicle stability control apparatus disclosed in the above-identified publication is arranged such that the vehicle operator""s manipulation of the vehicle is predominant over the control performed by the vehicle running stability control apparatus, in the event that a collision of the vehicle with the obstacle is highly expected in the process of the vehicle running stability control, so that the vehicle collision with the obstacle can be prevented, rather than the vehicle running or turning stability control is continued. Accordingly, the apparatus assures safe running of the vehicle even under severe running conditions beyond the vehicle running stability control. However, the apparatus relies upon an adequate manipulation of the vehicle operator to clear the obstacle by brake application to the vehicle and/or operating the steering wheel. In some emergency cases, the vehicle operator may bet at a loss or get puzzled with a hazardous running condition of the vehicle, and cannot take an appropriate measure to adequately control the vehicle. If the vehicle operator did not manipulate the vehicle at all under such a hazardous running condition, the vehicle running stability control would be continued, leading to a possibility of the vehicle collision with the obstacle. When the vehicle-operator""s manipulation is performed, the vehicle running stability control is terminated, but the vehicle collision with the obstacle cannot be prevented if the manipulation is not adequate.
It is therefore an object of the present invention to provide a vehicle stability control apparatus which assures safe running of the vehicle without an adequate manipulation of the vehicle by the vehicle operator in the event of a determination that there is a risk of a collision of the vehicle with an obstacle or a deviation of the vehicle from the nominal running path or traffic lane of the vehicle.
The above object may be achieved by a vehicle stability control apparatus according to any one of the following modes of the present invention, each of which is numbered like the appended claims and depends from the other mode or modes, where appropriate, to indicate and clarify possible combinations of elements or technical features. It is to be understood that the present invention is not limited to the technical features or any combinations thereof which will be described for illustrative purpose only. It is to be further understood that a plurality of elements or features included in any one of the following modes of the invention are not necessarily provided all together, and that the invention may be embodied without some of the elements or features described with respect to the same mode.
(1) A vehicle stability control apparatus comprising a vehicle running stability control device for controlling an automotive vehicle for stable running of the vehicle, and a braking device for applying a brake to the vehicle, said apparatus further comprising:
a hazard detecting device for detecting a hazardous condition of the vehicle; and
an automatic brake application device operable to activate the braking device, when the hazard detecting device has detected the hazardous condition of the vehicle at least during an operation of the vehicle running stability control device.
In the conventional vehicle stability control apparatus, an operation of the vehicle running stability control device is terminated upon determination that there is a risk of a collision of the vehicle with an obstacle, if the vehicle operator has operated the braking device and also operated the steering wheel during the operation of the vehicle running stability control device, and if the direction of operation of the steering wheel permits the vehicle to clear the obstacle.
In the vehicle stability control apparatus according to the above mode (1) of this invention, the vehicle is automatically braked by the automatic brake application device, to assure a safe state of the vehicle, without an adequate manipulation of the vehicle by the vehicle operator, upon detection of a hazardous condition of the vehicle during an operation of the vehicle running stability control device, for instance, in the event of determination that there is a risk of a collision of the vehicle with an obstacle or a deviation of the vehicle from the nominal running path, during an operation of the vehicle running stability control device. The automatic brake application device may or may not be operated to automatically brake the vehicle upon detection of the hazardous condition of the vehicle while the vehicle running stability control device is not in operation.
(2) A vehicle stability control apparatus according to the above mode (1), wherein the hazard detecting device includes an obstacle detecting device for detecting an obstacle in front of the vehicle as seen in a running direction of the vehicle, and the automatic brake application device is operated to activate the braking device, when an output of the obstacle detecting device at least during an operation of the vehicle running stability device indicates that there is a risk of a collision of the vehicle with the obstacle.
In the vehicle stability control apparatus according to the above mode (2), the vehicle is automatically braked by the automatic brake application device, to prevent the collision of the vehicle with the obstacle, without a manipulation of the vehicle by the vehicle operator, in the event of determination that there is a risk of the vehicle collision while the vehicle running stability control device is in operation. The automatic brake application device may or may not be operated in the event of determination of the presence of the risk of the vehicle collision while the vehicle running stability control device is not in operation.
(3) A vehicle stability control apparatus according to the above mode (2), wherein the automatic brake application device is operated during an operation of the vehicle running stability control device, when the output of the obstacle detecting device indicates that there is the risk of the collision of the vehicle with the obstacle.
In the vehicle stability control apparatus according to the above mode (3), the automatic brake application device is operated when it is determined that there is a risk of the vehicle collision with the vehicle while the vehicle running stability control device is in operation to improve the running stability of the vehicle. The operation of the vehicle running stability control device means that the vehicle is running in some hazardous condition. Accordingly, when the output of the obstacle detecting device indicates a risk of the vehicle collision with the obstacle during an operation of the vehicle running stability control device, it is generally difficult for the vehicle operator to manipulate the vehicle, that is, to operate the braking device and the steering wheel, so as to safely clear the obstacle. In other words, the vehicle operator""s manipulation of the vehicle is not necessarily sufficient or effective to prevent the vehicle collision with the obstacle. In the present vehicle stability control apparatus, on the other hand, the automatic brake application device assures an adequate brake application to the vehicle to safely prevent the vehicle collision with the obstacle, even in such an event.
(4) A vehicle stability control apparatus according to the above mode (1), wherein the hazard detecting device includes a vehicle-deviation determining device for determining whether there is a risk of a deviation of the vehicle from a nominal running path of the vehicle, the automatic brake application device being operable to activate said braking device, when an output of the vehicle-deviation determining device at least during an operation of said vehicle running stability control device indicates that there is said risk of the deviation of the vehicle from the nominal running path.
In the vehicle stability control apparatus according to the above mode (4), the vehicle is automatically braked by the automatic brake application device, to prevent the deviation of the vehicle from the nominal running path, without a manipulation of the vehicle by the vehicle operator, in the event of determination that there is a risk of the vehicle deviation while the vehicle running stability control device is in operation. The automatic brake application device may or may not be operated in the event of determination of the presence of the risk of the vehicle deviation while the vehicle running stability control device is not in operation.
(5) A vehicle stability control apparatus according to the above mode (4), wherein the automatic brake application device is operated during an operation of the vehicle running stability control device, when the output of the vehicle-deviation determining device indicates that there is the risk of the deviation of the vehicle from the nominal running path.
In the vehicle stability control apparatus according to the above mode (5), the automatic brake application device is operated when it is determined that there is a risk of the vehicle deviation from the nominal running path, while the vehicle running stability control device is operated to improve the running stability of the vehicle. The operation of the vehicle running stability control device means that the vehicle is running in some hazardous condition, in which the vehicle operator rarely has an intention to change the traffic lane from the present one to the adjacent one. That is, the vehicle deviation indicated by the output of the vehicle-deviation determining device is not desired by the vehicle operator, and must therefore be prevented by automatic brake application to the vehicle by operation of the automatic brake application device.
(6) A vehicle stability control apparatus according to the above mode (4) or (5), wherein the vehicle-deviation determining device includes a lane detecting device for detecting a lane-defining line which defines a traffic lane on which the vehicle is running, the vehicle-deviation determining device determining that there is a risk of the deviation of the vehicle from the nominal running path, when an angle between the lane-defining line detected by the lane detecting device and a longitudinal direction of the vehicle is larger than a predetermined upper limit.
The determination as to whether there is a risk of deviation of the vehicle from the nominal running path may be effected by detecting the traffic lane on which the vehicle is running, and estimating the running path along which the vehicle is going to run. However, the vehicle-deviation determining device of the vehicle stability control apparatus according to the above mode (6) of the invention is adapted to make the determination on the basis of the longitudinal direction of the vehicle as compared with the detected lane-defining line. This manner of determination is relatively simple, and the vehicle-deviation determining device is available at a reduced cost. However, the vehicle-deviation determining device may include a running-path estimating device for estimating the vehicle running path, as well as the lane detecting device.
(7) 7. A vehicle stability control device according to the above mode (6), wherein the vehicle-deviation determining device further includes a running-path estimating device for estimating an actual running path of the vehicle, on the basis of a yaw rate of the vehicle.
The vehicle-deviation determining device is capable of determining, with increased reliability, whether there is a risk of the vehicle deviation from the nominal running path, on the basis of not only the angle of the longitudinal direction of the running vehicle with respect to the lane-defining line, but also the angular velocity of the turning vehicle.
(8) A vehicle stability control device according to the above mode (6) or (7), wherein the vehicle-deviation determining device includes an image obtaining device for obtaining image data representative of an image of a scene in front of the vehicle as seen in a longitudinal direction of the vehicle, and an image-data processing device for processing the image data to determine a lane-defining line which defines a traffic lane on which the vehicle is running.
The image-data processing device of the vehicle-deviation determining device in the vehicle stability control apparatus according to the above mode (8) may be arranged to process the image data to determine the lane-defining line, on the basis of a difference in brightness or luminance between the lane-defining line and the roadway surface on which the vehicle is running. In this respect, it is noted that the lane-defining line is usually a white line having a comparatively high degree of luminance.
(9) A vehicle stability control device according to any one of the above modes (1)-(8), further comprising running stability control terminating device for terminating the operation of the vehicle running stability control device when the braking device is activated by the automatic brake application device.
If the automatic brake application to the vehicle by the braking device activated by the automatic brake application device were effected concurrently with the vehicle running stability control by the vehicle running stability control device, the automatic brake application and the vehicle running stability control would interfere with each other, causing an undesirable result regarding the running condition of the vehicle. In the vehicle stability control apparatus according to the above mode (9), the vehicle running stability control device is turned off when the automatic brake application is initiated by activation of the braking device by the automatic brake application device, so that the hazardous condition of the vehicle such as the vehicle collision with an obstacle or the vehicle deviation from the nominal running path can be prevented with increased reliability and stability.
(10) A vehicle stability control apparatus according to any one of the above modes (1)-(9), wherein said automatic brake application device controls said braking device to brake all of a plurality of wheels of the vehicle such that a total braking force generated by the all of said plurality of wheels is equal to a predetermined maxim value.
In the vehicle stability control apparatus according to the above mode (10), the vehicle is effectively braked with the maximum braking force, to assure improved safety of the vehicle, when the hazard detecting device has detected a hazardous condition of the vehicle such as the vehicle collision with an obstacle or the vehicle deviation from the nominal running path.
(11) A vehicle-collision preventing apparatus for preventing a collision of an automotive vehicle with an obstacle, comprising:
a braking device for applying a brake to the vehicle;
a running-path estimating device for estimating a running path of the vehicle;
an obstacle detecting device for detecting an obstacle existing in front of the vehicle and in the running path of the vehicle estimated by the running-path estimating device;
a vehicle speed detecting device for detecting a running speed of the vehicle;
a vehicle-collision determining device for determining, on the basis of the running speed of the vehicle detected by the vehicle speed detecting device, whether there is a risk of a collision of the vehicle with the obstacle detected by the obstacle detecting device on an assumption that the vehicle is braked at a predetermined reference deceleration value; and
an automatic brake application device operable to activate the braking device to brake the vehicle at a deceleration value whose absolute value is larger than that of the reference deceleration value, when the vehicle-collision determining device has determined that there is the risk of the collision of the vehicle with the obstacle.
In the vehicle-collision preventing apparatus according to the above mode (11) of this invention, the vehicle is automatically braked upon determination that there is a risk of a collision of the vehicle with an obstacle, irrespective of whether a vehicle running stability control is effected or not. The reference deceleration value may be a fixed value, for instance, about 0.5 G, or a variable which varies depending upon the detected vehicle running speed and/or other parameters indicative of the vehicle running condition. The deceleration value to be established by the automatic brake application under the control of the automatic brake application device may be slightly larger than the reference deceleration value, so that the vehicle can be braked to prevent the vehicle collision with high stability. Alternatively, the deceleration value to be established by the automatic brake application may be a highest possible value in order to minimize the vehicle running distance required to stop the vehicle. Further, the deceleration value to be established by the automatic brake application may be determined depending upon the detected vehicle running speed, a distance between the vehicle and the obstacle, and other parameters.
(12) A vehicle-collision preventing apparatus according to the above mode (11), wherein the running-path estimating device, the vehicle speed detecting device and the vehicle-collision determining device are kept operated even after an operation of the braking device is initiated by the automatic brake application device, the vehicle-collision determining device including deceleration increasing means for increasing the absolute value of the deceleration value to be established by the operation of the braking device under the control of the automatic brake application device, as long as the vehicle-collision determining device keeps determining that there is the of the collision of the vehicle with the obstacle.
In the vehicle-collision preventing apparatus according to the above mode (12), the deceleration value to be established by the operation of the braking device under the control of the automatic brake application device is gradually increased from a predetermined initial value. The running-path estimating device and the vehicle-collision determining device are adapted to repeatedly estimate the vehicle running path and determine where there is a risk of the vehicle collision, on the basis of the currently established deceleration value, each time the deceleration value is updated, i.e., increased. As long as the vehicle-collision determining device continues to determine that there is a risk of the vehicle collision, the deceleration value to be established by the automatic brake application is increased. If the vehicle-collision determining means determines that there is no longer a risk of the vehicle collision, the presently established deceleration value is maintained. Thus, the present arrangement does not cause an unnecessarily high rate of increase in the deceleration value of the vehicle. The deceleration value to be established by the automatic brake application may be determined on the basis of the predetermined reference value used by the vehicle-collision determining means for effecting the initial determination. Alternatively, the deceleration value to be established by the automatic brake application may be determined on the basis of the initial value of deceleration initially established immediately after the automatic brake application is initiated, or the last determined or established value. The deceleration value to be established may be incremented by a predetermined amount, or may be increased by an amount depending upon the currently detected vehicle speed or the currently detected actual deceleration value.
(13) A vehicle-deviation preventing apparatus for preventing a deviation of an automotive vehicle from a nominal running path of the vehicle, comprising:
a braking device for applying a brake to the vehicle;
a vehicle-deviation determining device for determining whether there is a risk of a deviation of the vehicle from a nominal running path; and
an automatic brake application device operable to activate the braking device to brake the vehicle when the vehicle-deviation determining device has determined that there is the risk of the vehicle deviation from the nominal running path.
In the vehicle-deviation preventing apparatus according to the above mode (13) of this invention, the vehicle is automatically braked by the braking device under the control of the automatic brake application device when a risk of a vehicle deviation is detected, irrespective of whether a vehicle running stability control is performed or not.
(14) A vehicle-deviation preventing apparatus according to the above mode (13), further comprising an alarm indicator device operable when the vehicle-deviation determining means has determined that there is the risk of the deviation of the vehicle, to warn an operator of the vehicle that there is the risk.
In the vehicle-deviation preventing apparatus according to the above mode (14), the vehicle operator is warned of a fact that the automatic brake application to the vehicle is initiated to avoid the vehicle deviation from the nominal running path. Accordingly, the vehicle operator can be made ready for the automatic brake application. The alarm indicator device is preferably adapted to provide a warning indication before the automatic brake application is initiated. However, the warning indication may be provided before or upon the initiation of the automatic brake application, or after the initiation of the automatic brake application, for instance, immediately before or at the time when deceleration of the vehicle as a result of the automatic brake application is initiated. Where the warning indication is provided before the initiation of the automatic brake application, this warning indication is effective to prevent the vehicle operator from falling asleep while driving the vehicle.
(15) A vehicle-deviation preventing apparatus according to the above mode (13) or (14), further comprising an operator-controlled member, and an automatic-brake-application inhibiting device for inhibiting an operation of the automatic brake application device when the operator-controlled member is operated.
The feature of the vehicle-deviation preventing apparatus according to the above mode (15) of the invention is equally applicable to the apparatus according to any one of the above modes (1)-(12).
If the vehicle is automatically braked under the control of the automatic brake application device in response to a determination that there is a risk of the vehicle deviation from the nominal running path, when the vehicle operator is manipulating the steering wheel for the purpose of changing the traffic lane on the roadway from the present one to the adjacent one. In the apparatus according to the above mode (15) wherein the automatic-brake-application inhibiting device is provided, the automatic brake application to the vehicle contrary to the intention of the vehicle operator can be avoided. If the automatic brake application is inhibited after it is initiated, it is desirable to cancel an effect of the automatic brake application. The operator-controlled member whose operation triggers the automatic-brake-application inhibiting device may be an accelerator pedal, a steering wheel or other operator-controlled member usually provided on the vehicle. Where the accelerator pedal is utilized as the operator-controlled member to inhibit the automatic brake application, the inhibiting device inhibits the automatic brake application when the accelerator pedal is depressed. A depression of the accelerator pedal indicates the vehicle operator""s intention to accelerate the vehicle, rather than decelerating the vehicle. Where the steering wheel is utilized as the operator-controlled member to inhibit the automatic brake application, the inhibiting device inhibits the automatic brake application when the steering wheel is rotated in a direction which is opposite to the direction in which the vehicle is deviating with respect to the nominal running path. Where the other operator-controlled members are utilized as the operator-controlled member to inhibit the automatic brake application, the inhibiting device inhibits the automatic brake application when an operation of the operator-controlled member satisfies a predetermined condition. The operator-controlled member may be a member exclusively provided for inhibiting the automatic brake application. It is also appreciated that the vehicle-deviation determining device may be operated in response to a control signal applied to a signaling device provided to indicate the direction of turning of the vehicle. In this case, for example, the vehicle-deviation determining device does not determine that there is a risk of the vehicle deviation, if the vehicle deviation follows the intention of the vehicle operator, more specifically, if the direction of deviation detected by the vehicle-deviation determining device is the same as the direction of turning of the vehicle represented by the control signal applied to the signaling device.
(16) A vehicle-deviation preventing apparatus according to the above mode (13), further comprising:
an alarm indicator device operable when the vehicle-deviation determining device has determined that there is the risk of the deviation of the vehicle, to warn an operator of the vehicle that there is the risk;
an operator-controlled member; and
an automatic-brake-application inhibiting device for inhibiting an operation of the automatic brake application device when the operator-controlled member is operated,
and wherein the automatic brake application device activates the braking device when a predetermined time has passed without an operation of the operator-controlled member after the alarm indicator device is operated.
In the vehicle-deviation preventing apparatus according to the above mode (16) wherein the vehicle operator is given a warning indication that the automatic brake is applied to the vehicle, before the automatic brake application is initiated. Accordingly, the vehicle operator who has been given the warning indication may easily inhibit the automatic brake application to the vehicle contrary to the vehicle operator""s intention. The predetermined time between the moment of activation of the alarm indicator device and the moment of inhibition of the automatic brake application may be a predetermined fixed time which is considered necessary to allow the vehicle operator to decide whether the automatic brake application should be effected or not. The predetermined time may be changed depending upon the detected vehicle speed or the expected length of time during which the vehicle has deviated from the nominal running path. It is desirable that the vehicle-deviation determining device be adapted to determine the presence of a risk of the vehicle deviation, at a relatively early point of time so that the safe running state of the vehicle can be secured even after the predetermined time has passed after the activation of the alarm indicator device. In addition, it is desirable that the automatic brake application can be terminated when the operator-controlled member is operated even after the automatic brake application has been initiated.
(17) A vehicle-deviation preventing apparatus according to the above mode (16), wherein the vehicle-deviation determining device includes a time estimating portion for estimating a length of time during which the vehicle has deviated from the nominal running path, and a time determining portion for determining the above-indicated predetermined time on the basis of the estimated length of time.
In the vehicle-deviation preventing apparatus according to the above mode (16), the predetermined time between the moment of activation of the alarm indicator device and the moment of inhibition of the automatic brake application is determined on the basis of the estimated length of time during which the vehicle has deviated from the nominal running path. This arrangement permits the automatic brake application to be initiated before its inhibition by the automatic-brake-application inhibiting device if the estimated length of time is relatively short, and permits the automatic-brake-application inhibiting device to inhibit the automatic brake application depending upon the operation of the operator-controlled member, if the estimated length of time is relatively long.
(18) A vehicle stability control apparatus according to any one of the above modes (1)-(10), further comprising a vehicle stop indicator device operable when the braking device is operated by the automatic brake application device, for providing an indication that the vehicle is being braked.
(19) A vehicle-collision preventing apparatus according to the above mode (11) or (12), further comprising a vehicle stop indicator device operable when the braking device is operated by the automatic brake application device, for providing an indication that the vehicle is being braked.
(20) A vehicle-deviation preventing apparatus according to any one of the above modes (13)-(16), further comprising a vehicle stop indicator device operable when the braking device is operated by the automatic brake application device, for providing an indication that the vehicle is being braked.
In the apparatus according to any one of the above modes (18)-(20), the vehicle stop indicator device provides an indication of the automatic brake application to the vehicles so that the operators operating the trailing vehicles following the vehicle in question can know that the vehicle in question is being braked for an emergency stop. Thus, the vehicle stop indicator device assures improved safety of running of the trailing vehicles. The vehicle stop indicator device may include a hazard lamp whose illumination is visible by the operators of the trailing vehicles.